Brave face! Heidi Klum puts on strong front for outing with her children despite rumored split from Martin Kristen

And Heidi Klum made that perfectly clear as she put on a brave face to take her four little ones out for an early morning stroll in Brentwood, California on Sunday, in the wake of reports that she has split from her bodyguard boyfriend Martin Kristen.

The 40-year-old supermodel even managed a bold smile as she gripped her children's hands, with her youngest daughter Lou looking cute in a creative bright pink dancing ensemble.

Sunday funday! Heidi Klum stepped out with her children Leni, Johan, Henry and Lou on a stroll in Los Angeles, with little Lou getting cute and creative with a pink ensemble

Klum herself looked to be putting
her independent woman foot forward in a dark and domineering
ensemble with a distinctively biker-girl feel.

The
America's Got Talent judge wore a black tank featuring the visage of an
intimidating leopard, sneering at any onlookers as it sat nestled
amongst an elaborate design of printed bling to form a cool rocker look.

Rocking the dark side? The 40-year-old supermodel, who is rumoured to have split from bodyguard boyfriend Martin Kristen, looked strong in a biker-chic outfit

Slinging a chic blazer over the
ensemble to account for the chilly winter morning and carrying a
sizeable black handbag on her shoulder, the pretty blonde model strode
confidently through the streets.

With
one hand she gripped a takeout beverage, and with another
she held the hands of her little ones, who had snacks and drinks of
their own.

Lou
- who is Heidi's youngest daughter she had with ex-husband Seal - was
dressed up in a cute pink ensemble made up of shiny shorts and polka-dot
leg warmers to go with her pink ballet shoes, clearly showing
off a little individual style flair.

Juggling act: The busy mother juggles being a parent with her career as a model and television host

The German-born model is rumoured to have called time on her 18-month relationship with Martin Kristen last month.

The
model and her former bodyguard got together after she split from singer
husband Seal back in 2012, but they are said to have broken up 'a few
weeks ago.'

A
friend of Heidi's told People magazine: 'Martin was there for her
during a challenging time in her life and it was something she will
always be grateful for.

'Life is about timing. He was
incredibly supportive and they were there for each other, but they're
moving on now. They still have a great friendship.'

The couple were last seen together on New Year's Eve, when Heidi posted an Instagram shot of the pair in wigs.

Heidi
and Martin were practically inseparable over the past year and a half,
when he was frequently seen doting on her four children, Leni, aged nine,
Johan, aged seven, Henry, aged eight, and Lou, aged four.

In happier times: Heidi is said to have called time on her 18-month romance with Martin, her former bodyguard, in January

Trying to say something? Heidi Klum uploaded this Instagram snap of her car stereo playing an extremely loved-up love song by John Legend - All Of Me - on Sunday morning